Gas distribution systems, in particular natural gas distribution systems, typically transport gas from a producer to a consumer along a series of pipes and through a series of valves. Each gas distribution system may include one or more regulator valves that control the pressure of the gas within the distribution system. Normally, the gas is transmitted at a high pressure through the system. However, the pressure of the gas must be reduced prior to final distribution to the consumers. This pressure reduction is typically accomplished at pressure reducing stations within local networks.
In many cases, these pressure reducing stations include some sort of safety device to shut off the flow of gas. Most commonly, emergency shut-off valves are used for this purpose. The emergency shut-off valve is generally disposed upstream of the pressure regulating valve so that the emergency shut-off valve may prevent gas from reaching the pressure regulating valve in the event of a problem. Typically, emergency shut-off valves have a closure member, such as a poppet, that is mounted on a rotatable shaft to move the poppet between an open position, which allows the flow of fluid through the valve, and a closed position, which prevents the flow of fluid through the valve. Generally, a spring acts on the shaft and the poppet to store rotational energy, and the spring rotates the shaft and poppet from the open position to the closed position, and a locking mechanism is used to maintain the poppet in the open position. When it is desired by a user to cut off flow through the emergency shut-off valve, the locking mechanism is disengaged by manually displacing a cable coupled to the locking mechanism. With the locking mechanism disengaged, the stored rotational energy of the spring quickly rotates the shaft and poppet from the open position to the closed position, thereby cutting off flow through the emergency shut-off valve.